The present invention relates generally to agricultural balers and more particularly to round balers which form cylindrical bales using one or more movable belts and/or rollers disposed in a bale-forming chamber.
Round balers have become quite prevalent for their capability of producing a conveniently sized cylindrical bale, very often automatically wrapped with a sheeting material such as net or film. Prior art round balers generally have a bale-forming chamber defined by an apron comprising an array of side-by-side belts, transverse slats trained on chains, a plurality of rolls or a combination of these various elements, e.g., rolls and belts. Crop material, such as hay, is picked up from the ground as the baler travels across the field, and is fed into a fixed or expandable chamber where it is rolled up to form a compact cylindrical hay package. While still inside the bale-forming chamber in its compacted form, the outer surface of the package is wrapped with twine or other wrapping material, such as film or net, prior to ejection of the wrapped bale from the chamber onto the ground for subsequent handling.
U.S. Pat. Nos. 4,870,812 and 5,367,865 issued to Jennings et al., disclose prior art round balers having an expandable bale chamber defined by a pair of fixed sidewalls, and a plurality of side-by-side belts cooperating with a series of transverse rolls, mounted between a pair of pivotally mounted arms commonly known as a sledge. The chamber includes an inlet opening in the front through which crop material is fed. Also included is a pair of take up arms pivotally mounted on the main frame, between which arms a pair of guide rolls are journalled. A biasing force on the take up arms urges the outer surfaces of the guide rolls against the belts to maintain tension and thereby prevent slack from occurring in the belts during expansion and contraction of the chamber.
As the bale increases in size in the chamber, an increasing proportion of the belts spans between the two guide rolls and around the periphery of the bale. Proper belt tensioning is critical as the bale grows to maintain proper belt tracking and evenly apply tension across the bale width, a a complex task given that upwards of fifteen feet of belt length may be wrapped around the bale periphery between the two guide rolls. Furthermore, the shape of the portion of the bale chamber defined by the belts during the bale formation period is generally flat as a result of the belts spanning between two guide rolls. To overcome the limitations of this asymmetric bale chamber shape, movement of the belts and an aggressive belt surface are required to adequately urge the incoming crop material in the proper direction to begin rolling to form the bale. Aggressive belt surfaces which help promote initial bale core formation also tends to pull more crop material from the incoming crop mat resulting in increased wastage.
It would be desirable to provide a mechanism for guiding the roll belts in a round baler which reduces the unguided belts spans thereby improving belt tracking. Additional advantages would be realized in a mechanism for guiding the roll belts in a round baler that creates an optimum bale core forming configuration in the bale chamber to improve bale core formation. Still further advantages would be realized through an improved roll belt guide combined with an improved bale core forming configuration that enables rolling motion of the incoming crop material to be more easily initiated thereby reducing crop wastage and input power requirements.